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Marseille, France

Zarzoso-Lacoste D.,Aix - Marseille University | Corse E.,Batiment Villemin | Vidal E.,Center Saint Charles | Vidal E.,Center Ird Of Noumea
Molecular Ecology Resources | Year: 2013

While the morphological identification of prey remains in predators' faeces is the most commonly used method to study trophic interactions, many studies indicate that this method does not detect all consumed prey. Polymerase chain reaction-based methods are increasingly used to detect prey DNA in the predator food bolus and have proven efficient, delivering highly accurate results. When studying complex diet samples, the extraction of total DNA is a critical step, as polymerase chain reaction (PCR) inhibitors may be co-extracted. Another critical step involves a careful selection of suitable group-specific primer sets that should only amplify DNA from the targeted prey taxon. In this study, the food boluses of five Rattus rattus and seven Rattus exulans were analysed using both morphological and molecular methods. We tested a panel of 31 PCR primer pairs targeting bird, invertebrate and plant sequences; four of them were selected to be used as group-specific primer pairs in PCR protocols. The performances of four DNA extraction protocols (QIAamp® DNA stool mini kit, DNeasy® mericon food kit and two of cetyltrimethylammonium bromide-based methods) were compared using four variables: DNA concentration, A260/A280 absorbance ratio, food compartment analysed (stomach or faecal contents) and total number of prey-specific PCR amplification per sample. Our results clearly indicate that the A260/A280 absorbance ratio, which varies between extraction protocols, is positively correlated to the number of PCR amplifications of each prey taxon. We recommend using the DNeasy® mericon food kit (QIAGEN), which yielded results very similar to those achieved with the morphological approach. © 2013 Blackwell Publishing Ltd.

Mevy J.P.,Aix - Marseille University | Mevy J.P.,Center Saint Charles | Bessiere J.M.,National Graduate School of Chemistry, Montpellier | Dherbomez M.,Laboratoire SESNAB
Journal of Essential Oil-Bearing Plants | Year: 2012

The composition of the essential oil obtained from the aerial parts of Chrysanthellum americanum was analysed by GC-MS. Sixty-five compounds were identified from the hydrodistillate; caryophyllene oxide (20%), hexa-2,4-dienol (10%), β-caryophyllene (6%), α-pinene (4.5%) and verbenol (4.5%) were found as the main constituents. The oil was further tested against five microorganisms and two of them showed a significant inhibitory effect. The growth of Candida albicans and Saccharomyces cerevisiae were inhibited at 100 μgml-1 broth, suggesting that the oil is potentially antifungal. The chemiluminescence analysis carried out reveals that this volatile oil was slightly antioxidant with an IC50 value of 530 mM compared to that of the reference; α-tocopherol. Hence the involvement of the oil chemical constituents in the obtained biological activities is discussed in this report. © 2012, Har Krishan Bhalla & Sons.

Zarzoso-Lacoste D.,CNRS Mediterranean Institute for Biodiversity and Ecology Marine and Continental | Zarzoso-Lacoste D.,British Petroleum | Zarzoso-Lacoste D.,French National Center for Scientific Research | Bonnaud E.,CNRS Ecology, Systematic and Evolution Laboratory | And 11 more authors.
Biological Conservation | Year: 2016

On islands, invasive predators, particularly feral cats and rats, are key drivers of bird population decline and extinction. Diet studies can be used to assess predator impacts on prey populations. Here we first evaluated the resolution of morphological identification (Class to Species) of bird remains in cat and rat diet studies. We also analysed the effect of predator size/type (cat vs rat) and sample type (faecal vs stomach contents) on the taxonomic level of bird identification. We found that difficulty in identifying bird remains significantly increased with taxonomic resolution (from Class to Species) for both predators. Bird identification was more accurate in cat than in rat diets and no sample-type effect was detected in cat diets. Second, we developed a set of molecular resources (DNA sequence database and bird-specific primer pairs) to detect and identify bird DNA. We tested and validated primer pairs' taxonomic coverage and specificity using in silico and in vitro analyses. The performances of morphological and molecular methods were then compared in a case study of cat and rat diet samples collected on Niau Atoll (French Polynesia). Our results highlight the efficiency of the molecular method in both detection and high-resolution identification of birds in predator diet samples. As robust qualitative and quantitative diet analyses are required to accurately assess predator impacts on prey populations, we recommend combining morphological and molecular methods to maximise bird detection, identification and quantification, especially when rare or threatened birds are at stake. © 2015 Elsevier B.V..

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